Combination burning rate catalyst and curative

ABSTRACT

Epoxyethylferrocene used as a combination burning rate catalyst and curative in a solid propellant composition.

ite atent 1191 1111 3,762,969 Sayies 1 1 Oct. 2, 1973 1 COMBHNATHON BURNING RATE 3,087,844 4/1963 Hudson et a1 1. 149/19 CATALYST AND CURATIVE 3,109,761 11/1963 Cobb et a1. 149/19 3,305,523 2/1967 Burnside .v 149/19 X Inventor: David y n i A 3,322,804 5/1967 P111011 149/109 x [73] Assignee: The United States of America as represented by the Secretary of the Army, Washington, DC. Primary ExaminerBenjamin R. Padgett Att0rney-Harry M. Saragovitz, Edward J Kelly, [221 Flled' 1968 Herbert Berl and James T. Dcaton [21] Appl. No.1 707,358

[52] US. Cl 149/192, 149/20, 149/21,

149/44, 102/102 [57] ABSTRACT [51] Int. Cl C06d 5/06 [58] Field of Search 149/19, 20, 42, 44,

149/11 2, 21; 102/102 Epoxyethylferrocene used as a combtnatlon burnmg rate catalyst and curative in a solid propellant composi- [56] References Cited UNITED STATES PATENTS 3,002,830 10/1961 Barr 149/19 10 Claims, N0 Drawings COMBINATION BURNING RATE CATALYST AND CURATIVE DEDICATORY CLAUSE The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to me of any royalty thereon.

BACKGROUND OF THE INVENTION This invention relates to a novel burning rate catalyst for use in solid propellant compositions, and in particular to one which also functions as a curative.

Prior art solid propellant compositions have primarily employed cross-linking agents such as tris(methylaziridinyl)phosphine oxide or tris(oxiranyl)paraaminophenol. Other imines and epoxy (oxiranyl) compounds have been used as curatives on occasion. These solid propellant compositions also utilize'a burning rate catalyst such as ferrocene or normal-butylferrocene. However, to date there have been no efforts to synthesize a combination burning rate catalyst and curative.

Accordingly, it is the principal object of this invention to provide an improved burning rate catalyst.

It is a particular object of this invention to provide an improved burning rate catalyst which also functions as a crosslinking agent or curative.

SUMMARY OF THE INVENTION It has been discovered that epoxyethylferrocene can be used as a combination buring rate catalyst and curative in a solid propellant composition.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Epoxyethylferrocene can be used as a combination burning rate catalyst and curative in a solid propellant composition. The solid propellant composition also contains ammonium perchlorate (or other inorganic oxidizer), a metal staple additive such as aluminum, a binder, another burning rate catalyst, if desired, and a processing aid. The binder is formed from a prepolymer reacted with the crosslinking agent in the presence of a polymerization catalyst.

The propellant compositions of this invention are preferably composite (typically having a carboxylor hydroxyl-terminated polybutadiene, acrylate, acrylic acid and polybutadiene or polyurethane binder) or composite crosslinkable double-base (typically having a nitrocellulose binder which has been reacted with a plasticizer such as nitroglycerine, and other additives). However, the epoxyethylferrocene can also be used as a substitute for a portion of another oxidizer (e.g., potassium perchlorate or ammonium nitrate) in a doublebase or other propellant.

The preferred ingredient concentration ranges of propellant compositions of this invention are (approximate weight percentages):

Ammonium perchlorate 60-72 Aluminum 2-20 (optional) Binder 9-20 Epoxyethylferrocene 1-15 Of course, the total weight percentages of the ingredients must be 100.

If desired, conventional burning rate catalysts (or other additives) such as copper chromite can be incorporated into the propellant composition in small amounts.

The following table shows a conventional highburning rate propellant composition (Composition A) compared with Compositions B and C of this invention.

Compo- Compo- Compolngredient sition sition sition A B C Carboxyl-terminated polybutadiene prepolymer 12.3 12.3 12.3 Tris(methylaziridinyl)phosphine oxide 0.3 (1 5 (l 5 Tris(oxiranyl)para-aminophenol 0.3 Epoxyethylferrocene 10.0 8.5 Normal-butylferrocene 7.0 lron Linoleate 0.1 0.1 0.1 Ammonium Perchlorate 66.0 63.1 64.6 Aluminum 14.0 14.0 14.0

The synthesis of epoxyethylferrocene can be effected by using a one to one molar ratio of acetyl chloride to ferrocene according to the following reaction scheme: acetyl chloride+ferrocene Friedel-Craft condensation acetylferrocene acetylferrocene Reduction with LiAlH4 l-ferrocenyl- 1- ethanol M l-ferrocenyl-l -ethanol Dehydration with a mixture of acetic and trifiuoroaeetic anhydrides Vinylferrocene Peroxidation with hydrogen peroxide epoxyethylferrocene By modifying the experimental conditions, bis(epoxyethyl) ferrocene can also be synthesized. This involves using about twice the molar quantities of reactant with ferrocene. Similarly, tris(epoxyethyl)ferrocene may be synthesized by using three times the molar quantities of reactant with ferrocene.

In general, any lower epoxyalkylferrocene, lower being defined as having one to five carbons in the sidechain of the alkyl group, may be employed in accordance with this invention.

The combination burning rate catalyst and curative of this invention can also be used with solid propellant compositions in which a diisocyanate is used as a chain extender or crosslinking agent. An example of such a diisocyanate is toluene diisocyanate.

Various other modifications and variations of this invention will become obvious to those skilled in the art in the light of the above teachings, which modifications and variations are within the spirit and scope of this invention.

I claim:

1. A solid propellant composition comprising an inorganic oxidizer selected from ammonium perchlorate, potassium perchlorate, and ammonium nitrate, a binder selected from carboxyl-terminated polybutadiene, hydroxyl-terminated polybutadiene, acrylate, acrylic acid and polybutadiene, polyurethane, and nitrocellulose, and a combination burning rate catalyst and curative comprising a lower epoxyalkylferrocene.

2. The solid propellant composition of claim 1 wherein said epoxyalkylferrocene is epoxyethylferrocene, bis(epoxyethylferrocene) or tris(epoxyethyl)ferrocene.

prises a metal staple in an amount of at least about 2 percent by weight.

8. The solid propellant composition of claim 7 wherein said epoxyethylferrocene is present in an amount of from about 1 to 15 percent by weight.

9. The solid propellant composition of claim 8 wherein said metal staple is aluminum.

10. The solid propellant composition of claim 9 wherein said ammonium perchlorate is present in an amount of from about 60 to about 72 percent by weight and wherein said prepolymer is present in an amount of from about 9 to about 20 percent by weight. 

2. The solid propellant composition of claim 1 wherein said epoxyalkylferrocene is epoxyethylferrocene, bis(epoxyethylferrocene) or tris(epoxyethyl)ferrocene.
 3. The solid propellant composition of claim 2 wherein said epoxyalkylferrocene is epoxyethylferrocene.
 4. The solid propellant composition of claim 3 wherein said inorganic oxidizer is ammonium perchlorate.
 5. The solid propellant composition of claim 4 wherein said binder is formed from a carboxyl-terminated polybutadiene prepolymer.
 6. The solid propellant composition of claim 5 wherein said prepolymer is crosslinked with tris(methylaziridinyl)phosphine oxide.
 7. The solid propellant composition of claim 6 wherein said propellant composition additionally comprises a metal staple in an amount of at least about 2 percent by weight.
 8. The solid propellant composition of claim 7 wherein said epoxyethylferrocene is present in an amount of from about 1 to 15 percent by weight.
 9. The solid propellant composition of claim 8 wherein said metal staple is aluminum.
 10. The solid propellant composition of claim 9 wherein said ammonium perchlorate is present in an amount of from about 60 to about 72 percent by weight and wherein said prepolymer is present in an amount of from about 9 to about 20 percent by weight. 